Conventionally, the tool disclosed in Patent Document 1 has been used as an indexable rotary cutting tool for machining a three-dimensional shape of a die, etc. The cutting insert disclosed in Patent Document 1 has a cutting edge shape which allows for machining with a reduced amount of cutting depth and an increased feed speed, i.e., high-feed machining. Thus, this cutting insert is suited to roughing on a workpiece with high efficiency.
Meanwhile, an example of another indexable rotary cutting tool for machining a three-dimensional shape is disclosed in Patent Document 2. The cutting insert disclosed in Patent Document 2 has a substantially circular-arc shape in which, in a top view, a cutting edge thereof is projected outward. An indexable rotary cutting tool having a cutting insert which has the above edge shape mounted thereon is generally referred to as a radius cutter (or a radius end mill). In general, as to a radius cutter, a substantially circular-arc-shaped cutting edge thereof is capable of cutting, with high accuracy, a workpiece surface to be machined in three-dimensional machining, such as copy machining, and therefore, such radius cutter is suited not only to roughing but also to finishing.